The field of this invention relates to musical instruments and more particularly to a device to assist in the repairing of pianos.
Within pianos there is a plurality of side by side elongated members which are generally referred to as piano keys with there being a piano key for each different musical note on the piano. The piano key has a fingertip section which is commonly referred to as "the ivories." The inward portion of the piano key which extends within the cabinet portion of the piano terminates in a striker member adapted to strike one or more wire strings to produce a desired musical note. Intermediate the striking end of the piano key and the fingertip section of the piano (at approximately the mid point thereof) is an opening. The opening is mounted upon a pin and it is about this pin that the piano key pivots as the key is struck. There is a separate pin for each key and these pins are mounted on a longitudinal bar which is fixed within the cabinet of the piano.
Attached to the piano key in the area of this opening and connecting with the pin is a key button which normally is constructed of wood. This key button includes within the longitudinal opening a felt bushing which provides for movement of the pin during the pivoting motion. Not only does this opening provide for movement of the pin, but it guides the movement in a precise manner. It is necessary that the movement of the pin with respect to the longitudinal slot of the key button be in a plane parallel to the plane of the movement of the fingertip section of the key as it is depressed. If the movements are not parallel, the key will tend to contact the keys on either side thereof and this contact may detract from the produced tone of the key. Also, it is possible that two or more keys will then move together. Also, a key that is restrained from free movement because of non-parallel alignment of the key button slot will produce a "touch" or feeling that is unacceptable to the player.
This problem is complicated since the piano keys are not all straight longitudinal members but frequently contain various angles of deflection so that the striker portion of the key is offset from the fingertip portion of the key.
The replacement of the key buttons is required due to possible releasing of the adhesive securing the key button to the key or the fact that the felt bushing in the longitudinal slot within the key button or the slot itself has become excessively worn, or the fact that the key button may have broken from use. In any instance, the key button must be replaced.
The normal procedure for replacing a key button is to remove the key from the piano upon which the worn or misplaced key button is located. The old key button is removed and a new key button is replaced thereon. The placement can be either accomplished manually by visually observing what is believed to be the correct replacement, or a separate alignment apparatus can be employed which requires removing of at least one adjacent key for reference. The manual procedure is undesirable as the key button cannot be precisely located upon the key to the degree of accuracy that is necessary and also the other method requires the additional step of removing an adjacent key which in and of itself is not required to be removed.